/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Lotus
 * Development Corporation., http://www.lotus.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.xpath.objects;

import org.w3c.dom.*;

/**
 * <meta name="usage" content="general"/>
 * This class represents an XPath number, and is capable of
 * converting the number to other types, such as a string.
 */
public class XNumber extends XObject
{

  /** Value of the XNumber object.
   *  @serial         */
  double m_val;

  /**
   * Construct a XNodeSet object.
   *
   * @param d Value of the object
   */
  public XNumber(double d)
  {

    super();

    m_val = d;
  }

  /**
   * Tell that this is a CLASS_NUMBER.
   *
   * @return node type CLASS_NUMBER 
   */
  public int getType()
  {
    return CLASS_NUMBER;
  }

  /**
   * Given a request type, return the equivalent string.
   * For diagnostic purposes.
   *
   * @return type string "#NUMBER" 
   */
  public String getTypeString()
  {
    return "#NUMBER";
  }

  /**
   * Cast result object to a number.
   *
   * @return the value of the XNumber object
   */
  public double num()
  {
    return m_val;
  }

  /**
   * Cast result object to a boolean.
   *
   * @return false if the value is NaN or equal to 0.0
   */
  public boolean bool()
  {
    return (Double.isNaN(m_val) || (m_val == 0.0)) ? false : true;
  }

  /**
   * Cast result object to a string.
   *
   * @return "NaN" if the number is NaN, Infinity or -Infinity if
   * the number is infinite or the string value of the number.
   */
  public String str()
  {

    if (Double.isNaN(m_val))
    {
      return "NaN";
    }
    else if (Double.isInfinite(m_val))
    {
      if (m_val > 0)
        return "Infinity";
      else
        return "-Infinity";
    }

    double num = m_val;
    String s = Double.toString(num);
    int len = s.length();

    if (s.charAt(len - 2) == '.' && s.charAt(len - 1) == '0')
    {
      s = s.substring(0, len - 2);

      if (s.equals("-0"))
        return "0";

      return s;
    }

    int e = s.indexOf('E');

    if (e < 0)
      return s;

    int exp = Integer.parseInt(s.substring(e + 1));
    String sign;

    if (s.charAt(0) == '-')
    {
      sign = "-";
      s = s.substring(1);

      --e;
    }
    else
      sign = "";

    int nDigits = e - 2;

    if (exp >= nDigits)
      return sign + s.substring(0, 1) + s.substring(2, e)
             + zeros(exp - nDigits);

    if (exp > 0)
      return sign + s.substring(0, 1) + s.substring(2, 2 + exp) + "."
             + s.substring(2 + exp, e);

    return sign + "0." + zeros(-1 - exp) + s.substring(0, 1)
           + s.substring(2, e);
  }

  /**
   * Return a string of '0' of the given length
   *
   *
   * @param n Length of the string to be returned
   *
   * @return a string of '0' with the given length
   */
  static private String zeros(int n)
  {

    char[] buf = new char[n];

    for (int i = 0; i < n; i++)
    {
      buf[i] = '0';
    }

    return new String(buf);
  }

  /**
   * Return a java object that's closest to the representation
   * that should be handed to an extension.
   *
   * @return The value of this XNumber as a Double object
   */
  public Object object()
  {
    return new Double(m_val);
  }

  /**
   * Tell if two objects are functionally equal.
   *
   * @param obj2 Object to compare this to
   *
   * @return true if the two objects are equal 
   *
   * @throws javax.xml.transform.TransformerException
   */
  public boolean equals(XObject obj2) throws javax.xml.transform.TransformerException
  {

    // In order to handle the 'all' semantics of 
    // nodeset comparisons, we always call the 
    // nodeset function.
    if (obj2.getType() == XObject.CLASS_NODESET)
      return obj2.equals(this);

    return m_val == obj2.num();
  }
}